I am still new to the autoLISP language, but have been teaching myself quite a bit, and have had help from fellow co-workers who have been using autoLISP for years. AIRFOIL.LSP is the first program with any significance to the general public that I have written. It will plot the outline of an airfoil with the airfoil’s name, from a .DAT type file which are readily available on-line. There may be some variations in the format, I am not sure. I have ~2400 of these files, and they all are tab delimited, with the airfoil description on the first line, and with x-y points that start at 1,0 and end at 1,0. This is the format I have assumed in my program.
There sometimes arises a need for a very torsionally rigid wing. This can be accomplished by laying out the ribs so that they are not perpendicular to the main spar, and form a truss like structure. There are many variations on this theme, but they all share angled ribs. When a rib is angled in relation to the airflow, you do not necessarily get the airfoil profile your are expecting parallel to the direction of the airflow as you can imagine. I have never been able to find a program capable of modifying an airfoil profile such that when a rib is cut and placed at an angle, the actual section through the chord of the wing will be the desired profile. AIRFOIL.LSP will correct for this, if you specify the acute angle between the spar and the rib, and it will stretch the airfoil in the x direction accordingly. If you were then to cut a section through your wing, you will end up with the profile you intended.
I know for a fact that this program is compatible with AUTOCAD 2006 and 2007 and very likely more recent versions. I also know it is NOT compatible with AUTOCAD 2000, as the pedit command has changed since then. Those are the only platforms I have at my disposal to test it on. If you are running something different and AIRFOIL.LSP is not working, please don’t hesitate to let me know the nature of the problem, and I can attempt to modify it to work for you.
Because of limitations in the file type that wordpress lets you upload, I have had to change the file extension to .JPG. To use this program, just download it and change the extension back to .LSP You can download it from here: AIRFOIL.LSP I have also uploaded an example airfoil .DAT file here: BE6407E.DAT Same problem with file extensions applies here, just change it to .DAT
This is an example of what you can expect. These are both the same profile and chord, but the lower profile has been angled at 60 deg. to direction of airflow.
